We haven't really started yet. I am going to actually start him at the first grade level until he gets the hang of it, and see how quickly he progresses through it. He thinks at the third grade level or so, but he is missing certain things that he hasn't really been exposed to much (mostly money and time), although I think he'll soak those up quickly once he starts.
The third grade materials we are working with are a nice combination of math facts and extensions that make the worksheets fun. We are also just at the very beginning of the workbook, so he is reviewing some second grade stuff. For instance, last week one of his homework sheets was a series of adding four sums to get an answer, each of which had a letter next to it. He then had to fill in the right letter for each sum in a series of blanks, which gave him the answer to a riddle. He loved it. Another sheet was finding all of the vertical and horizontal pairs of numbers in a number grid that added up to a certain number.
I agree with you to some degree about the math fact memorization, but what I have found is that he is somewhat limited in his math thinking by NOT having simple addition facts memorized. It is very obvious when he just knows a fact (e.g. 4+4 or 5+5), versus having to figure it out every time (e.g. 7+8). I think it will be very useful to him to have those facts at his fingertips. Same thing for multiplication, although we haven't really worked on that outside of the occasional word problem that he's come across. He knows the concept, but not the process.
